A two-stage amplifier, such as an on-chip voltage regulator, is conventionally compensated by setting a dominant pole at the output of the first stage. The dominant pole may be created using either Miller compensation or lead-lag compensation. In a conventional two-stage amplifier with varying load currents, the compensation capacitor can result in an adjustable pole in the frequency response. The pole is adjusted for maximum stability in the compensation system; either Miller or lead-lag is suitable. In either compensation scheme, the non-dominant pole is directly related to the transconductance of the second stage of the amplifier, which requires a minimum current in the second stage amplifier in order to guarantee a finite transconductance.
With varying load currents in the second stage, the minimum current is overhead of the amplifier in all cases and, thus, the power dissipation may be higher than necessary. Increased power dissipation may cause reduced battery life and/or excess heat dissipation.